8
on Cancer (AJCC) staging of esophageal and esophagogastric
junction epithelial cancers, only tumor involving the esophagogas-
tric junction with epicenter located at the 2 cm proximal to car-
dia (i.e., Siewert type I and II) is considered as esophageal cancer.
Tumor with epicenter located at more than 2 cm to cardia (Siewert
type III) will be considered as stomach cancer, even if the esopha-
gogastric junction is involved [ 1 ].
Radiotherapy (RT) is commonly used in treatment of esopha-
geal cancer, either as curative treatment or for palliation. For cura-
tive treatment, RT is often used in combination with chemotherapy
and/or surgery as multi-modalities treatment. In the past, simple
anterior-posterior opposing conventional fields may be used.
However, conventional field treatment is not optimal for the com-
plicated anatomy and avoiding normal organs. Thus, nowadays,
conventional technique is limited in use mainly for palliation.
Three-dimensional conformal radiotherapy (3DCRT) or intensity
modulated radiotherapy (IMRT) is commonly employed in
modern- day RT treatment. Image guided radiotherapy (IGRT)
may also be considered to account for the movement of the esoph-
ageal tumor with breathing. This chapter focuses on radiotherapy
for adenocarcinoma in the distal esophagus.The lower thoracic esophagus is bordered superiorly by the inferior
pulmonary veins and inferiorly by the stomach. Endoscopically, the
lower thoracic esophagus starts at around 30 cm distal to incisor to
the esophagogastric junction, which is at around 40 cm from inci-
sor. Radiotherapy to the distal esophagus will involve radiation to
normal tissues both in the thorax and in the abdomen. In the tho-
rax, the distal esophagus is bordered by the heart anteriorly, verte-
brae (spinal cord) posteriorly, and the lungs on both sides. These
are organs at risk (OARs) in planning for radiotherapy. Inferiorly,
the esophagus is connected to the stomach. Other organs that may
be irradiated in the abdomen include the left lobe of liver and may
be the left kidney.
The esophagus has an extensive, longitudinal interconnecting
system of lymphatics lining in the mucosa and submucosa, which
communicates with the lymphatic channels in the muscle layers.
Skip metastases with up to 8 cm or more “normal” mucosa in
between gross tumor and micrometastases are possible [ 2 ]. To
cover for microscopic/submucosal lymphatic spread of disease,
large longitudinal margins are required. The proximal margin can
be 4–5 cm beyond gross tumor. A larger margin will be required if
subsequent esophagectomy is not planned. The inferior margin
can go into the stomach and can be reduced to 2–3 cm.
The primary direction of lymphatic flow for distal esophagus is
toward the abdomen. Mediastinal lymph nodes involvement above
the carina is uncommon. Primary nodal metastases usually involve
paraesophageal nodes and paracardial lymph nodes for primary1.1 Consideration
of Anatomy
and Lymphatic Spread
in Radiotherapy
Dora L. W. Kwong and K. O. Lam